Alicia Baldessari

Lubricants from chemically modified vegetable oils.

This work reports laboratory results obtained from the production of polyols with branched ether and ester compounds from epoxidized vegetable oils pertaining to annual, temperate climate crops (soybean, sunflower and high-oleic sunflower oils), focusing on their possible use as components of lubricant base stocks. To this end, two different opening reactions of the epoxide ring were studied. The first caused by the attack with glacial acetic acid (exclusively in a single organic phase) and the second using short-chain aliphatic alcohols, methanol and ethanol, in acid media. Both reactions proceed under mild conditions: low synthesis temperature and short reaction times and with conversions above 99%. Spectroscopic (NMR), thermal (DSC) and rheological techniques were used to characterize the oils, their epoxides and polyols, to assess the impact of the nature of the vegetable oil and the chemical modifications introduced, including long-term storage conditions. Several correlations were employed to predict the viscosity of the vegetable oils with temperature, and good agreement with the experimental data was obtained.

One-pot biocatalyzed preparation of substituted amides as intermediates of pharmaceuticals

A lipase-catalyzed procedure is described for the one-pot conversion of carboxylic acids into substituted amides via in-situ formation of the ethyl ester and subsequent aminolysis. The procedure was optimized for the preparation of tetrahydro-N-[3-(methylamino)-propyl]-2-furancarboxamide, an intermediate in the synthesis of Alfuzosin, a reducing agent of symptoms associated with benign prostatic hypertrophy. This methodology proved to be general and can be applied to open-chain, cyclic, hydroxy-, amino-, dicarboxylic, various chain lengths, and unsaturated acids. Moreover, the enzyme shows a regioselective behavior in relation to primary and secondary amino groups. The procedure involved the treatment of the corresponding carboxylic acid with ethyl alcohol in presence of immobilized Candida antarctica lipase followed by addition of amine. The amide is obtained in good yields and regioselective way.

Enzymatic deacetylation of steroids bearing labile functions

Abstract Lipase from Candida cylindracea and Candida antarctica catalyzes the removal of acetyl groups from 3β-acetoxypregn-5-en-20-one and 3β-acetoxy-20-(S)-hydroxycholest-5-en-23-one through a transesterification reaction in organic solvents.

Chemo- and stereoselective reduction of β-keto esters by spores and various morphological forms of Mucor rouxii

We report the efficient enantioselective reduction of a number of β-ketoesters by mycelial and yeast-like forms of the dimorphic fungus Mucor rouxii in a whole-cell process. Mycelial cells, grown in aerobiosis, were efficient in water, whereas the yeast-like cells, grown in anaerobic medium, were both efficient in water and in organic solvents. Almost 100% of conversion with 97% of enantiomeric excess of the (S) forms of the reduced β-ketoesters was obtained at 15 g biomass (wet weight)/mmol substrate in two hours. The fungal spores, which are the physiologically resistant form of the fungus, also catalyzed the reductive process efficiently and stereoselectively. The freeze-dried as well as the warm-air dried yeast-like cells, rehydrated in a small volume of water, maintained the same efficiency and selectivity of the reaction in organic solvents as the fresh biomass up to at least 4 months.

Lipase-catalyzed regioselective preparation of fatty acid esters of hydrocortisone

A series of fatty acid derivatives of hydrocortisone has been prepared by an enzymatic methodology. Nine 21-monoacyl products and one 3,11,17-triacetyl derivative, nine of them novel compounds, were obtained in a highly regioselective way through lipase-catalyzed esterification, transesterification and alcoholysis reactions. The influence of various reaction parameters such as acylating agent: substrate ratio, enzyme: substrate ratio, solvent, temperature and nature of acylating agent and alcohol was evaluated. Among the tested lipases, Candida antarctica lipase appeared to be the most appropriate and showed a high efficient behavior especially in a one-pot transesterification. The advantages presented by this methodology, such as mild reaction conditions and low environmental impact, make the biocatalysis a convenient way to prepare acyl derivatives of hydrocortisone. These lipophilic compounds are potential products in the pharmaceutical industry.

Lipases as Efficient Catalysts in the Synthesis of Monomers and Polymers with Biomedical Applications

Fil: Garcia Linares, Guadalupe Eugenia. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Unidad de Microanalisis y Metodos Fisicos en Quimica Organica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Unidad de Microanalisis y Metodos Fisicos en Quimica Organica; Argentina

Enzymatic synthesis of bile acid derivatives and biological evaluation against Trypanosoma cruzi

Enzyme catalysis was applied to synthesize derivatives of three bile acids and their biological activity was evaluated as growth inhibitors of the protozoan Trypanosoma cruzi. Twelve mono-, diacetyl and ester derivatives of deoxycholic, chenodeoxycholic and lithocholic acid, seven of them new compounds, were obtained through lipase-catalyzed acetylation, esterification and alcoholysis reactions in very good to excellent yield and a highly regioselective way. Among them, acetylated ester products, in which the lipase catalyzed both reactions in one-pot, were obtained. The influence of various reaction parameters in the enzymatic reactions, such as enzyme source, acylating agent/substrate ratio, enzyme/substrate ratio, solvent and temperature, was studied. Some of the evaluated compounds showed a remarkable activity as Trypanosoma cruzi growth inhibitors, obtaining the best results with ethyl chenodeoxycholate 3-acetate and chenodeoxycholic acid 3,7-diacetate, which showed IC50: 8.6 and 22.8 μM, respectively. In addition, in order to shed light to bile acids behavior in enzymatic reactions, molecular modeling was applied to some derivatives. The advantages showed by the enzymatic methodology, such as mild reaction conditions and low environmental impact, make the biocatalysis a convenient way to synthesize these bile acid derivatives with application as potential antiparasitic agents.

Lipase-catalyzed Preparation of Biologically Active Esters of Dehydroepiandrosterone

A series of acyl esters derivatives of dehydroepiandrosterone have been prepared by an enzymatic methodology. The acyl chain had a length that varied from two to eighteen carbon atoms. The C18 derivative could be saturated or unsaturated. Following this biocatalytic approach we have also obtained a chloropropionyl derivative. We have observed that several lipases catalyzed esterification and transesterification reactions of dehydroepiandrosterone with carboxylic acids or alkyl carboxylates. The advantages presented by this methodology such as mild reaction conditions, economy and low environmental impact, make biocatalysis a convenient way to prepare acyl derivatives of DHEA with biological activity.

Chemoenzymatic synthesis and biological evaluation of 2- and 3-hydroxypyridine derivatives against Leishmania mexicana.

A series of hydroxyalkyl and acyloxyalkyl derivatives of 2- and 3-hydroxypyridine was synthesized and their biological activity was evaluated as growth inhibitors of protozoan Leishmania mexicana. Thirty novel compounds were obtained through a chemoenzymatic methodology in two reaction steps. The influence of various reaction parameters in the enzymatic step, such as enzyme source, acylating agent/substrate ratio, enzyme/substrate ratio, solvent and temperature, was studied. Some of the evaluated compounds showed a remarkable activity as Leishmania mexicana growth inhibitors, obtaining the best results with the acetylated derivatives. The advantages showed by the enzymatic methodology, such as mild reaction conditions and low environmental impact, make the biocatalysis a convenient way to prepare these derivatives of substituted pyridines with application as potential antiparasitic agents.

Lipase-catalyzed synthesis of medium- and long-chain diesters of 2-oxoglutaric acid

Abstract The influence of various reaction parameters, such as alcohol-to-substrate ratio, enzyme-to-substrate ratio, solvent and temperature, on the enzymatic preparation of a series of novel medium- and long-chain esters of 2-oxoglutaric acid has been evaluated. Among the tested lipases, those from Candida antarctica and Carica papaya appeared to be the best catalysts. Mild reaction conditions and low environmental impact make the biocatalytic procedure a convenient way to prepare the reported products, which are potential fat substitutes in the food industry.